A mere 100 facilities, out of 20,000, produced one third of U.S. industry's toxic air pollution in 2014. Another 100 released one third of industry's greenhouse gas emissions, among 7,000 installations that discharge the gas. And according to an investigation by the Center for Public Integrity that created the rankings, 22 “super-polluter” sites appeared on both lists (noted below). Many are coal-fired power plants, and some rank high because they are very large. This group is responsible for a significant chunk of U.S. industrial air pollution. (Since 2014 eight of the 178 facilities have closed, but none were super-polluters.) Researchers at the center also used census data to show that most of the 100 facilities on the toxics list are located in poor neighborhoods—where incomes are lower than the national average. The good news is that cleaning up the sites could make a big dent in toxic compounds that are implicated in respiratory illnesses and in the country's contribution to climate change. The researchers say that existing regulations are sufficient, but weak enforcement must improve.

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